4-5 days in Anilao for macro is better than anything I've seen in Cambodian and Vietnamese waters. Even the wide angle in the Mindoro area trumps anything I remember. The diving in Vietnam and Cambodia is mostly a must get wet and desperate variety. Good luck.
Thanks Drew. Looks like I'll need to head back that way for the diving.
As Drew said, Philippines might be a good choice. I would personally not pay for the diving in Cambodia or Vietnam.
Did you consider doing Angkor Wat while in Cambodia? I was there about a month ago and it blew my mind!
My tour ends in Siem Reap, with two days at Angkor Wat. Can't wait to see it. I guess I'll stay in Cambodia for a week after the tour.